Towards a modelling of RPV steel brittle fracture using crystal plasticity computations on polycrystalline aggregates

Vincent, L.; Libert, Maximilien; Marini, B.; Rey, Colette

doi:10.1016/j.jnucmat.2010.07.022

Cited by 24 publications

(16 citation statements)

References 12 publications

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“…In our approach, the probability of rupture (which depends on the tri-axial loading and temperature) is partly deduced from the distribution curves of the stress field. Applied by the same authors to compare unirradiated and irradiated materials rupture (Vincent et al, 2010), this model may be considered as a first step towards the study of an actual structure composed of several aggregates.…”

Section: Discussionmentioning

confidence: 99%

Temperature dependant polycrystal model application to bainitic steel behavior under tri-axial loading in the ductile–brittle transition

Libert

Rey

Vincent

et al. 2011

International Journal of Solids and Structures

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Keywords:Polycrystal plasticity Steel Mechanical behavior Bainite Cleavage fracture Fracture probability Pressure vessel steel Constraint effect a b s t r a c t A polycrystal finite element (FE) model describing the temperature evolution of low carbon steel is proposed in order to forecast the local mechanical fields as a function of temperature, for bainitic microstructure submitted to tri-axial loading. The model is designed for finite strains, large lattice rotations and temperatures ranging into the brittle-ductile transition domain. The dislocation densities are the internal variables. At low temperature in Body Centred Cubic (BCC) materials, plasticity is governed by double kink nucleation of screw dislocations, whereas at high temperature, plasticity depends on interactions between mobile dislocations and the forest dislocations. In this paper, the constitutive law and the evolution of the dislocation densities are written as a function of temperature and describe low and high temperature mechanisms. The studied aggregates are built from Electron Back Scattering Diffraction (EBSD) images of real bainitic steel. The aggregate is submitted to a tri-axial loading in order to describe the material at a crack tip. Mechanical parameters are deduced from mechanical tests. The local strain and stress fields, computed for different applied loadings, present local variations which depend on temperature and on tri-axial ratio. The distribution curves of the maximal principal stresses show that heterogeneities respectively increase with temperature and decrease with tri-axial ratio. A direct application of this model provides the evaluation of the rupture probability within the aggregate, which is treated as the elementary volume in the weak link theory. A comparison with the Beremin criterion calibrated on experimental data, shows that the computed fracture probability dispersion induced by the stress heterogeneities is of the same order than the measured dispersion. Temperature and stress tri-axiality ratio effects are also investigated. It is shown that these two parameters have a strong effect on fracture owing to their influence on the heterogeneous plastic strain. These inhomogeneities can initiate cleavage fracture.

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Section: Discussionmentioning

confidence: 99%

Temperature dependant polycrystal model application to bainitic steel behavior under tri-axial loading in the ductile–brittle transition

Libert

Rey

Vincent

et al. 2011

International Journal of Solids and Structures

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“…To do so, it is important to select a reference material that has been characterized using experimental tests. This material is called Euromaterial A and has been characterized in the PERFECT project [57] by Vincent et al in [58] and others [59,60]. The values of the constants found for this material can be consulted in Table 1.…”

Section: Simulated Behavior Of the Rpv Steelmentioning

confidence: 99%

Multiscale modeling of crystal plasticity in Reactor Pressure Vessel steels: Prediction of irradiation hardening

Monnet

Vincent

Gélebart

2019

Journal of Nuclear Materials

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In this paper, we present a set of equations capitalizing the multiscale modeling of the mechanical behavior of Reactor Pressure Vessel (RPV) steels before and after irradiation. The equations capture the temperature and strain rate sensitivity in addition to the contributions of microstructure features peculiar to RPV steels, such as carbides, initial dislocation network and the Hall-Petch grain size sensitivity. Dislocations are assumed to move on the {110} and {112} crystallographic planes and a simplified interaction matrix is proposed. The predicted yield stress is found in close agreement with a large number of experimental results over a large temperature range. Finally, contribution of radiation defects is accounted for using atomistic and dislocation dynamics results, revealing the effect of the solute cluster size and density on the mechanical behavior. Results are discussed and compared with an experimental database on neutron-irradiated RPV steels.

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“…MIBF model relies on crystal plasticity results in terms of heterogeneity of the stress field at the microstructure scale [10]. The concept, theory, and application of MIBF model are discussed in detail elsewhere [10,[24][25][26][27]. Generally, a compact tension (CT) specimen is modeled in the FEA framework to apply the MIBF.…”

Section: Application Of the Materials Modelmentioning

confidence: 99%

Brittle Fracture Model Parameter Estimation for Irradiated BCC Material through Dislocation Based Crystal Plasticity Model

Singh¹,

Robertson²,

Bhaduri³

2019

Frattura Ed Integrità Strutturale

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Radiation effects lead to a significant reduction in ductility during the life of the components used in nuclear reactors. A sharp change in fracture toughness at a lower temperature in Body Centered Cubic (BCC) materials as compared to Face Centered Cubic (FCC) materials is a major concern restricting their application in nuclear reactors in spite of having better thermal properties, excellent resistance to helium embrittlement and void swelling under higher dpa levels. In the present paper, such a strong temperature dependence of strain rate and flow stress in BCC materials is investigated numerically for both non-irradiated and irradiated conditions. The BCC materials subjected to radiation would undergo embrittlement, which raises the ductile to brittle transition (DBT) temperature up to or above the room temperature. In view of dislocations mobility being a fundamental property to determine the plastic behavior, the dislocations based material model is proposed, which has the physical rather than phenomenological basis. This material model accounts for both thermally activated and athermal regime dislocation mobilities in BCC materials and is capable of predicting the effect of irradiation-induced defects on the mobility of the dislocations which in turn directly affect the behavior of such materials. The relative change in the stress field due to the presence of irradiation defects in comparison to the nonirradiated case provides valuable input for brittle fracture model to develop advanced materials for nuclear application.

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Towards a modelling of RPV steel brittle fracture using crystal plasticity computations on polycrystalline aggregates

Cited by 24 publications

References 12 publications

Temperature dependant polycrystal model application to bainitic steel behavior under tri-axial loading in the ductile–brittle transition

Temperature dependant polycrystal model application to bainitic steel behavior under tri-axial loading in the ductile–brittle transition

Multiscale modeling of crystal plasticity in Reactor Pressure Vessel steels: Prediction of irradiation hardening

Brittle Fracture Model Parameter Estimation for Irradiated BCC Material through Dislocation Based Crystal Plasticity Model

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